What it is
Under the main joint at the base of each toe (the metatarsophalangeal joint) is a thick pad of tough, rubbery tissue called the plantar plate. Together with the ligaments at the sides of the joint, it is the joint's main support, stopping the toe bending back too far and keeping it in line.
A tear, usually where the plate joins the toe, lets the toe bend up and drift. Over time the joint can partly or fully dislocate, and the toe can cross over its neighbour (a crossover toe), lift off the floor (a floating toe) or curl (claw). Surgeons grade it from 0, pain and swelling in a stable joint, to 4, a dislocated joint with a fixed bent toe.
Sources 1, 2, 3
Who gets it
In 154 people at a UK foot clinic, 82% were women and the median age was 56. The second toe alone was affected in 64%, and the second toe was always involved when several toes were. In 169 people operated on for a crossover second toe, 86% were women, with an average age of 59, and bunions and big toe arthritis were more common than expected.
A review gives an average age of 60, or 50 in athletes, who make up 26% to 79% of cases depending on the clinic, and notes that it is often in both feet. High heels, bunions and a long second toe are commonly blamed, though the study of 169 crossover toes found no link with the length of the second metatarsal. An NHS board also lists extra weight, weak foot muscles, soft or flexible shoes, flat feet, inflammatory arthritis, running and jumping, and some jobs.
Sources 4, 5, 2, 3
How it feels and how it's recognised
Pain under the ball of the foot at the base of the second toe, like walking on a stone or a marble, with swelling, hard skin, a toe that drifts, splays or lifts, a weaker grip with that toe, and rubbing on top of the toe in shoes. It usually comes on gradually.
The drawer test is the key examination: the clinician steadies the foot bone and pushes the base of the toe upwards, and too much movement is a positive result. It's a useful test, but studies disagree on how accurate it is. In 90 people whose tears were repaired, it picked up 80.6% of tears and was rarely positive without one, but a study in cadavers found false positives in about 1 in 6, and a mildly positive test was found in about 1 in 3 people without symptoms and with a normal ultrasound scan.
A clinician may also check whether you can grip a strip of paper under the toe. A toe that crosses over its neighbour is a late sign: it was present in only 8% of confirmed tears.
Sources 3, 6, 7, 1, 2
Look-alikes
Morton's neuroma gives burning or shooting pain and numbness between the toes, usually the third and fourth, without a loose joint. The two can occur together, and in one review 3% to 14% of people with this kind of toe joint instability had had neuroma surgery that didn't help. Swelling in several toe joints, often in both feet with morning stiffness, points to joint inflammation such as rheumatoid arthritis.
Pain on top of a metatarsal bone that's worse with every step can be a stress fracture; collapse of the head of the second metatarsal (Freiberg's disease) affects teenagers and young adults; a swollen fluid sac between the bones can mimic both a neuroma and a plate tear; and gout can too. A big toe that was bent back in sport is turf toe.
Sources 2, 1, 8
What scans do and don't meanEmerging evidence
X-rays show indirect signs, such as a toe sitting up or drifting, and rule out bone problems. Ultrasound and MRI (magnetic resonance imaging) both did well in small studies checked against surgery or dissection: an MRI sign of scarring around the joint was right in about 91% of 45 joints, ultrasound was right in 79% of cadaver toes, and MRI with the toes bent up raised the pick-up rate from 75% to 100% in 15 patients.
Unlike many scan findings, a torn plate is rarely seen in people without forefoot pain: in 2% of 165 people having foot MRI for other reasons, against 28% of 53 with forefoot symptoms. Wear short of a tear was seen in 24% of 105 feet with ball-of-foot pain. So a tear on a scan that matches the examination usually matters, and a scan helps most when the diagnosis is unclear or surgery is planned.
Sources 2, 9, 10, 11, 12, 13, 3
How it usually goesEmerging evidence
It tends to progress slowly, from inflammation of the joint to partial and then full dislocation, which gives time to catch it early. An NHS board says ligament injuries in the foot can take 3 to 6 months to heal, and that the exercises can take up to 12 weeks to bring a clear improvement.
In the UK clinic, 64% were managed without surgery and did as well as those who had an operation. A case report followed a tear healing on MRI over a year of non-surgical care, and a professional dancer was dancing pain-free a year after a 16-week programme.
Sources 2, 3, 4, 14, 15